The invention concerns a magnet system having a power supply for charging a superconducting magnet coil.
Superconducting magnet coils, in particular for nuclear magnetic resonance experiments, are usually operated in persistent current mode. A power supply is connected to the magnet coil in preparation for operation of such a magnet system in order to charge the magnet coil with current. Subsequent thereto the power supply is separated and removed (see e.g. M. H. Wilson, Superconducting Magnets, Oxford, 1983, pages 272-274). The charging process of a superconducting magnet coil requires experience and technical skill. In particular, it is important to charge carefully in order to prevent a quench, i.e. a break-down of the superconducting state into the normally conducting state. Such a quench can lead to substantial coolant losses and costs time since the coolant must be refilled prior to newly charging.
In order to prevent a quench it is important to follow a particular charging program in order to charge the coil in a reliable but nevertheless rapid fashion. In addition the properties of a particular coil, in particular its field homogeneity and field stability, can be influenced by the charging procedure. In order to obtain as homogeneous a field for a particular coil as possible, the charging is to be carried out in accordance with a procedure individually tailored to this coil. This is usually done with the assistance of charging instructions. The individualized charging process is carried out by hand by, for example, a technician. Depending on the experience and reliability of the technician it is possible for the power supply to be operated in such a fashion that the magnet is not optimally charged or such that the charging process requires a significantly longer amount of time. In addition the reproduceability of the charging is not guaranteed completely and quenching of the magnet system is possible through improper charging of the coil.
It is consequently the purpose of the present invention to further improve a power supply of the above mentioned kind in such a fashion that the safety, quality, and speed of charging of the magnet coil is improved.